FeTiO₃-α-Fe₂O₃ solid solution films prepared by a reactive vapor deposition technique

FeTiO₃-α-Fe₂O₃ solid solution films were epitaxially formed on an α-Al₂O₃ (001) single crystalline substrate by activated reactive evaporation method. The films prepared at low substrate temperature of 500°C had the corundum structure where Fe and Ti ions occupied the cation sites randomly. While the Fe_2-xTi_xO₃ films with x ≥ 0.4 prepared at 700°C had the ilmenite structure where Fe and Ti ions were arranged in order. Only the films with the ordered Fe and Ti ions had large ferrimagnetic moments, though the observed spontaneous magnetization was less than a half of the ideal value expected from the fully ordered ions. Moreover the resistivity of the solid solution films dropped to 10^-1Ωcm due to the formation of the mixed valence states between Fe²⁺ and Fe³⁺. We revealed this system was one of the candidates for new oxide magnetic semiconductor films.